Specimen collections should be drawn at specified times to ensure accuracy. A patient intake of food, alcohol, tobacco, and medications can affect the results. In addition, posture, exercise, stress, and times of day can affect blood results.
Two tests that require fasting include various glucose evaluations and triglycerides.
Various types of glucose tests include fasting blood sugar, 2-hour postprandial blood sugar, random blood sugar, 2- or 3-hour oral glucose tolerance test, glucose challenge screening test, and intravenous glucose tolerance test.
The bleeding time test helps assess the ability of platelets to function during a bleeding episode. Situations that can cause a prolonged bleeding time include platelet dysfunction, decreased platelet number, fibrinogen disorders, and medications that hinder platelet functions.
To obtain blood for donation a phlebotomist must have special training, and the patient must meet certain physician requirements and must submit to a detailed patient interview and mini physical examination.
Patients may donate blood for their future use. This is known as autologous donation. Other patients may have blood drawn to treat a disease or disorder of the blood. This is known as therapeutic phlebotomy.
To perform blood alcohol testing the patient must consent or a legal document must be obtained. The site for venipuncture should be cleaned with something other than alcohol.
A forensic specimen is collected as evidence to help prove or disprove a link between an individual and/or between individuals and objects or places. Toxicology specimens are collected to detect poisons, drugs, or medications.
Therapeutic drug monitoring is done to ensure the correct amount of drug is given to produce the desired effect.
Other sites for blood specimen collection include heparin lock, arterial venous shunt, central venous therapy lines, and arterial punctures.
